1. Field of the Invention
The present invention relates to a substrate processing method and a substrate processing apparatus each for performing heat processing for a substrate such as a semiconductor wafer or the like in, for example, a low-oxygen atmosphere.
2. Description of the Related Art
In processes of semiconductor device fabrication, a layer insulating film is formed, for example, by an SOD (Spin on Dielectric) system. In this SOD system, a layer insulating film is formed by forming a coating film on a semiconductor wafer and performing chemical processing, heat processing, or the like by a sol-gel process or the like.
When a layer insulating film is formed by the sol-gel process in such an SOD system, the semiconductor wafer is transferred form a carrier station to a processing section and, for example, a coating solution in which colloids of TEOS (tetraethoxysilane) are dispersed in an organic solvent is applied onto the semiconductor wafer in a coating apparatus unit provided in the processing section. Thereafter the semiconductor wafer is transferred to an aging unit and subjected to gelling processing, and then transferred to a solvent exchange unit, where exchange of solvents is performed. Thereafter, a hot plate unit is performed heat processing for the semiconductor wafer as necessary. The semiconductor wafer on which a layer insulating film is completed as described above is returned to the carrier station.
In the hot plate unit of this SOD system, after the semiconductor wafer is transferred into a processing chamber and supported by raising and lowering pins, a lid body is lowered by a drive mechanism, whereby a lower end portion of the lid body and a top face of a hot plate closely contact each other to form the processing chamber having a certain capacity. Thereafter, prior to the heat processing, nitrogen gas that is an inert gas is supplied in order to prevent oxidation of the semiconductor wafer, whereby the inside of the processing chamber is exchanged for an atmosphere with a low oxygen concentration. Further, nitrogen gas is constantly introduced into the processing chamber, and additionally air is exhausted through an exhaust pipe provided at the lid body also during processing so that the heat processing is performed in an atmosphere with a certain low oxygen concentration.
However, in the aforesaid conventional art, a large amount of inert gas to be supplied is constantly required, which is not economically preferable. Further, since it often happens that processing is performed simultaneously in a plurality of processing chambers, if the amount of inert gas necessary for one processing apparatus increases, an extremely large amount of gas is required for the whole system including the above processing apparatuses, resulting in a case in which it is impossible to supply gas at once. Therefore, a design of the lid body shallow in depth is conceivable in order to decrease the capacity of the processing chamber. However, since the semiconductor wafer needs to be away from the hot plate in order not to be heated nor oxidized before the inside of the processing apparatus is exchanged for the inert gas, there is a limit to making the lid body shallow in depth.
An object of the present invention is to exchange an atmosphere in a processing chamber for an inert gas without increasing temperature of a semiconductor wafer and to reduce a supply amount of the inert gas while keeping a low oxygen concentration.
To achieve the above objects, a first aspect of the present invention is a substrate processing method for performing processing for a substrate on a mounting table using a substrate processing apparatus including the mounting table for mounting the substrate thereon, a lid body for forming a processing chamber with the mounting table, gas supply means for supplying gas into the processing chamber, and exhaust means for exhausting an atmosphere in the processing chamber, the substrate processing method comprising the steps of: forming the processing chamber between the mounting table on which the substrate is mounted and the lid body; and reducing a capacity of the formed processing chamber.
A second aspect of the present invention is a substrate processing apparatus comprising: a mounting table for mounting a substrate thereon; a lid body with a lower face side opened for forming a processing chamber with the mounting table; gas supply means for supplying gas into the processing chamber; exhaust means for exhausting an atmosphere in the processing chamber; a drive mechanism for relatively vertically moving the lid body and the mounting table; and means for controlling a capacity of the processing chamber formed between the mounting table on which the substrate is mounted and the lid body by relatively vertically moving the lid body and the mounting table by the drive mechanism.
In the present invention, for example, the lid body in the substrate processing apparatus is lowered with respect to the mounting table to thereby reduce the capacity of the processing chamber, so that the supply amount of gas supplied into the processing chamber can be reduced.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.